This invention relates to compositions and methods for preserving animal hides, in particular, protecting them against degradation resulting from microbiological growth.
Animal hides received by tanneries in excellent condition can be used for valuable end products and sold at a premium as compared to lesser quality hides. However, prior to arriving at a tannery, freshly stripped hides are typically washed and stored; during this period, such hides are susceptible to decomposition by microorganisms. Microbial growth on the hide surface and within the hide and blood vessels may cause irreparable damage resulting in lower quality hides having reduced value. Damaged hides may display holes or darkened areas, reduced hide strength, and altered stretching characteristics. Hair slippage, color, and integrity, all measures of hide quality, may also be adversely affected by microbial growth.
A variety of agents have been used for preserving hide quality but numerous detrimental effects are associated with their use. The oldest and most widely used preservation process is treatment of the hides with sodium chloride. Salt reduces the water content of the hides creating an adverse environment for microbial growth. Concentrated salt solutions also have a certain bactericidal activity. Typically, 0.3-0.6 kg sodium chloride per kg of wet hide is added to control microbial growth. However, the addition of such agents as sodium chloride also provokes hide shrinkage that may be considered a loss. Moreover, the sodium chloride is corrosive to equipment and its use results in significant, negative environmental impact on discharge or additional expense when removed prior to discharge.
The rot-preventing effect of salt can be enhanced by the addition of chemical biocidal or bactericidal agents, thereby reducing the amount of salt required. Such additives include, for example, naphthalene, p-chloro-m-creosol, sodium silicofluoride, ortanotin compounds, chlorinated phenols, pyridine derivatives, quaternary ammonium compounds, zinc salts, monochloroacetic acid, and many others. However, all of these additives require the concomitant use of a relatively high quantity of salt.
Likewise, antibiotics, such as tetracyclines, streptomycin, and penicillin, have also been proposed for use in preserving hides by inclusion in a hot brine solution. This method also contemplates optionally injecting the antibiotic into the animal prior to slaughter followed by immersion in the antibiotic-containing hot brine solution.
Numerous attempts to develop salt-free preservation processes have been largely unsuccessful. Such attempts include drying, solvent dehydration, bactericidal treatment, irradiation, and cooling. These processes have been generally unreliable for a variety of reasons, e.g., damage to the hides, toxicological and environmental safety problems, limited effectiveness, and/or economically unviable.
The present invention addresses the need to preserve hides without damage and eliminate the adverse economic and environmental impacts associated with the use of other agents and processes.